Franziskus is on the right track. It seems like you are not running your display (LCD or TFT, presumably) at the native resolution (e.g., a 17" TFT typically has a 1280x1024 resolution). This will make your details seem pixelated, and the fonts can be looking strange ("shading" around the edges to adjust for pixels that do not match 1-for-1).
The easy answer is to run at native resolution.
For CRT monitors, this is not usually a problem, since the way the pixels are created on the screen (e.g., the glowing phosphorous dots you see) is diffeent than the hardwired, discrete dots of a TFT screen. That means CRT (Cathode Ray Tube) monitors (the "normal", heavy glass tube monitors) will not have nearly as much (in fact, generally unnoticable) pixelation.
The reason RTW installed differently is beacuse of the hardware matrix it uses to adjust certain system performance 'tweaks', and it sensed something different after you re-installed, so it set a different resolution, and that made it appear pixelated.